Central venous catheter with heat exchange membrane

ABSTRACT

A central venous catheter includes coolant supply and return lumens which communicate coolant to and from first and second heat exchange membranes arranged along the distal segment of the catheter. The coolant in the heat exchange membranes removes heat from the patient. Additional lumens are provided for conventional central venous catheter uses.

RELATED APPLICATION

This Application is a CIP of U.S. patent application Ser. No.09/253,109, filed Feb. 19, 1999.

FIELD OF THE INVENTION

The present invention relates generally to methods and apparatus forcooling patients for therapeutic purposes, and more particularly tosystems for establishing central venous access while providing a meansfor cooling a patient.

BACKGROUND

It has been discovered that the medical outcome for a patient sufferingfrom severe brain trauma or from ischemia caused by stroke or heartattack is degraded if the patient's body temperature rises above normal(38° C.). It is further believed that the medical outcome for many suchpatients might be significantly improved if the patients were to becooled relatively quickly for a short period, e.g., 24-72 hours. Apartfrom the therapeutic benefits of hypothermia, the outcomes for braintrauma or ischemia patients that develop fevers is worse than forpatients that do not develop fevers. Consequently, temperaturemanagement for such patients is important, even when hypothermia is notto be used to treat the patients. Moreover, prophylactic short-termhypothermia might help patients undergoing minimally invasive heartsurgery and aneurysm surgery.

The affected organ, in any case, is the brain. Accordingly, systems andmethods have been disclosed that propose cooling blood flowing to thebrain through the carotid artery. An example of such systems and methodsis disclosed in co-pending U.S. patent application Ser. No. 09/063,984,filed Apr. 21, 1998, owned by the present assignee and incorporatedherein by reference. In the referenced application, various cathetersare disclosed which can be advanced into a patient's carotid artery andthrough which coolant can be pumped in a closed circuit, to remove heatfrom the blood in the carotid artery and thereby cool the brain. Thereferenced devices have the advantage over other methods of cooling(e.g., wrapping patients in cold blankets) of being controllable,relatively easy to use, and of being capable of rapidly cooling andmaintaining blood temperature at a desired set point.

As recognized in co-pending U.S. patent application Ser. No. 09/133,813,filed Aug. 13, 1998, owned by the present assignee and incorporatedherein by reference, the above-mentioned advantages in treating braintrauma/ischemic patients by cooling can also be realized by cooling thepatient's entire body, i.e., by inducing systemic hypothermia. Theadvantage of systemic hypothermia is that, as recognized by the presentassignee, to induce systemic hypothermia a cooling catheter or othercooling device need not be advanced into the blood supply of the brain,but rather can be easily and quickly placed into the relatively largevena cava of the central venous system.

Moreover, since many patients already are intubated with central venouscatheters for other clinically approved purposes anyway, providing acentral venous catheter that can also cool the blood, if only to managetemperature and thereby ameliorate fever spikes, requires no additionalsurgical procedures for those patients. A cooling central venouscatheter is disclosed in the present assignee's co-pending U.S. patentapplication Ser. No. 09/253,109, filed Feb. 19, 1999 and incorporatedherein by reference. The present invention is directed to such a device.

SUMMARY OF THE INVENTION

A heat exchange catheter, preferably made of urethane, includes acatheter body defining at least a coolant supply lumen and a coolantreturn lumen. First and second heat exchange membranes are disposedalong a distal portion of the catheter body, and the heat exchangemembranes communicate with one or more of the lumens. With thisstructure, coolant can be supplied to the heat exchange membranes viathe coolant supply lumen and received from the heat exchange membranesvia the coolant return lumen to effect a closed loop heat exchanger forcooling and/or warming a patient.

Preferably, the first and second heat exchange membranes define firstand second interiors respectively communicating with first and secondcoolant supply ports in the coolant supply lumen. Also, first and secondcoolant return ports are formed in the coolant return lumen, and coolantflows from the heat exchange membranes through the return ports. Atleast one anchor can be engaged with the catheter body to fasten thecatheter to a patient.

In addition to the coolant supply and return lumens, the catheter candefine a drug delivery lumen and a guide wire lumen. A connectormanifold can be engaged with the catheter body to interconnect thelumens with respective connector lines. More specifically, the connectormanifold defines plural channels, and each channel establishes arespective pathway for fluid communication between a respectiveconnector line and a respective lumen. As set forth in detail below, theanchor is on the connector manifold.

To provide for infusing medicament into a patient while simultaneouslycooling the patient, at least one drug delivery port is formed in thecatheter body. Preferably, the drug delivery port is formed at alocation that is between two adjacent heat exchange membranes toestablish a pathway for fluid communication from the drug delivery lumento a location outside the catheter body. If desired, additional drugdelivery ports can be formed along the length of the catheter.

In another aspect, a method for making a heat exchange catheter includesdisposing a multi-lumen catheter body in a connector manifold mold, anddisposing plural connector tubes in the connector manifold mold. Also,the method includes interconnecting a respective lumen with a respectiveconnector tube using a mandrel, and then directing a plastic materialinto the connector manifold mold. The mandrels are then removed, suchthat a respective channel is defined between each respective lumen andits connector line.

In another aspect, a method is disclosed for treating a patient. Themethod includes advancing a heat exchange catheter device into thepatient, and then circulating coolant through the catheter device whilepreventing infusion of the coolant directly into the patient'sbloodstream. Per the present invention, the catheter device includes aheat exchange region that is established by: one or more heat exchangemembranes, or one or more hollow fibers, or one or more chamber-definingenclosures.

In still another aspect, a catheter configured as a Swan-Ganz catheteror central venous catheter has at least one balloon-like membranedistally located on the catheter for heating or cooling blood in apatient. More particularly, the membrane defines an interiorcommunicating with a coolant supply lumen of the catheter and with acoolant return lumen of the catheter, to circulate coolant through theinterior of the membrane.

The details of the present invention, both as to its structure andoperation, can best be understood in reference to the accompanyingdrawings, in which like reference numerals refer to like parts, and inwhich:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the present cooling catheter,schematically showing a medicament source and coolant source in anexploded relationship with the catheter;

FIG. 2 is a cross-sectional view as seen along the line 2—2 in FIG. 1;

FIG. 3 is a cross-sectional view as seen along the line 3—3 in FIG. 1;and

FIG. 4 is a top view of the interior of the connector manifold, as seenalong the line 4—4 in FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring initially to FIG. 1, a therapeutic catheter system, generallydesignated 10, is shown for establishing and maintaining hypothermia ina patient, or for attenuating a fever spike in a patient and thenmaintaining normal body temperature in the patient. Commencing thedescription of the system 10 at the proximal end, as shown the system 10includes a cooling source 12 that can be a water-bath system or aTEC-based system such as either of the systems disclosed in co-pendingU.S. patent application Ser. No. 09/220,897, filed Dec. 24, 1998 andincorporated herein by reference, or U.S. patent application Ser. No.09/260,950, filed Mar. 2, 1999, also incorporated herein by reference.In any case, the coolant source provides coolant such as saline througha coolant supply line 14, and coolant is returned to the source 12 via acoolant return line 16. A catheter, generally designated 18, includes asource tube 20 terminating in a fitting such as a female luer fitting22. Also, the catheter 18 has a return tube 24 terminating in a fittingsuch a male luer fitting 26. The fittings 22, 26 can be selectivelyengaged with complementary fittings 28, 30 of the lines 14, 16 toestablish a closed circuit coolant path between the catheter 18 andcoolant source 12.

Additionally, the catheter 18 includes a guide wire and primary infusiontube 32 that terminates in a fitting such as a female luer 34. A guidewire 36 can be advanced through the tube 32 in accordance with centralvenous catheter placement principles, or medicament or other fluid canbe infused through the guide wire and primary infusion tube 32.Moreover, a secondary infusion tube 38 with female luer fitting 40 canbe selectively engaged with a medicament source 42 for infusing fluidfrom the source 42 through the secondary tube 38.

As discussed further below, the tubes 20, 24, 32, 38 are held in adistally-tapered connector manifold 44. As also set forth further below,the connector manifold 44 establishes respective pathways for fluidcommunication between the tubes 20, 24, 32, 38 and respective lumens ina catheter body 46.

A suture anchor 48 advantageously is formed on the connector manifold 44for suturing the catheter 18 to a patient in accordance with centralvenous catheter operating principles. In one intended environment, thesuture anchor 48 includes opposed ears 50 formed with respective sutureholes 52. Other equivalent anchor structure can be used to hold thecatheter 18 onto the patient, however, including surgical tape. When thecatheter is a so-called Swan-Ganz catheter, i.e., a catheter of the typedisclosed in U.S. Pat. No. 3,995,623, incorporated herein by reference,the anchor 48 typically would not be provided.

In cross-reference to FIGS. 1 and 2, the catheter body 46 includes atleast two lumens, and in the preferred embodiment the catheter body 46includes at least four lumens. More specifically, the catheter body 46defines a generally wedge- or triangular-shaped (in the transversecross-section shown) coolant supply lumen 54, a generally wedge-shapedcoolant return lumen 56, a round guide wire lumen 58, and a wedge-shapedsecondary infusion lumen 60. As mentioned above, however, the cathetercan be a Swan-Ganz catheter, in which case additional lumens can beprovided for Swan-Ganz catheter applications, including a lumen forinflating an anchoring balloon for holding the distal tip of thecatheter in an appropriate blood vessel for various heart-relatedmeasurements and another lumen for holding a wire or wires that areattached to one or more distally-located sensors, such as temperaturesensors, pressure sensors, gas sensors, and electrical sensors.

In any case, the connector manifold 44 establishes a pathway for fluidcommunication between the coolant supply tube 20 and the coolant supplylumen 54. Likewise, the connector manifold 44 establishes a pathway forfluid communication between the coolant return tube 24 and the coolantreturn lumen 56. Further, the connector manifold 44 establishes apathway for fluid communication between the guide wire and primaryinfusion tube 32, and the guide wire lumen 58, which terminates at anopen distal hole 62 defined by a distally tapered and chamfered distaltip 63 of the catheter body 46. Also, the connector manifold 44establishes a pathway for fluid communication between the secondaryinfusion tube 38 and the secondary infusion lumen 60, which terminatesat an infusion port 64 in a distal segment of the catheter body 46.Additional ports can be provided for each lumen 58, 60 along the lengthof the catheter.

Referring now to FIGS. 1 and 3, at least proximal and distal thin-walledheat exchange membranes 66, 68 are arranged along the last fifteen or socentimeters of the catheter body 46 and are bonded to the outer surfaceof the catheter body 46, with the infusion port 64 being located betweenthe heat exchange membranes 66, 68. Thus, each heat exchange membrane isabout six centimeters to seven and one-half centimeters in length, withthe heat exchange membranes being longitudinally spaced from each otheralong the catheter body 46 in the preferred embodiment shown.Essentially, the heat exchange membranes 66, 68 extend along most or allof that portion of the catheter 46 that is intubated within the patient.The heat exchange membranes can be established by a medical balloonmaterial.

The heat exchange membranes 66, 68 can be inflated with coolant from thecoolant source 12 as supplied from the coolant supply lumen 54, andcoolant from the heat exchange membranes 66, 68 is returned via thecoolant return lumen 56 to the coolant source 12. In their inflatedconfigurations, the heat exchange membranes define a diameter of aboutten French, and preferably no more than twelve French. Thus, the heatexchange membranes 66, 68 are relatively long and comparatively thin, toadvantageously avoid excessively blocking blood flow through the venacava while nevertheless effecting patient cooling.

As shown in FIG. 3, a wall 70 separates the coolant supply and returnlumens 54, 56. Taking the proximal heat exchange membrane 66 as anexample, a supply port 72 is formed in the catheter body 46 throughwhich coolant from the supply lumen 54 can flow into the interior 74 ofthe heat exchange membrane 66, as indicated by the arrows 76. Moreover,a return port 78 is formed in the catheter body 46, and coolant can flowout of the heat exchange membrane 66 through the return port 78 and intothe return lumen 56, as indicated by the arrows 80. As can beappreciated in reference to FIG. 3, for each heat exchange membrane 66,68, the respective coolant supply port is distal to the respectivecoolant return port, to optimize fluid flow and heat transfer, althoughif desired the direction of fluid flow can be in the opposite direction.Both the coolant supply and coolant return lumens 54, 56 terminateproximal to the distal tip 63. For example, the coolant return lumen 56can terminate just distal of the coolant return port for the distal heatexchange membrane 68, and the coolant supply lumen can terminate justdistal of the coolant supply port of the distal heat exchange membrane68.

In any case, it may now be appreciated that coolant is circulatedthrough the catheter device 18 in a closed loop. That is, infusion ofthe coolant directly into the patient's bloodstream is prevented. Asdetailed above, the catheter device includes a heat exchange regionestablished by one or more heat exchange membranes. Alternatively, theheat exchange region can: be established by or one or more hollowfibers, or one or more chamber-defining enclosures, such as metal orplastic bellows-type enclosures.

In the preferred embodiment, the components of the catheter 18 are madeof urethane, and more preferably are made of an aromatic,polyether-based polyurethane, although other suitable materials can beused. In a specific embodiment, the tubes 20, 24, 32, 38 are made ofTecothane TT-1095A made by Thermedics, Inc. of Woburn, Mass. Also, theheat exchange membranes 66, 68 are made of Pellethane 2363-65D, made byDow Chemical Corp. In contrast, the catheter body 46 is made ofTecothane TT-2055D-B20 with Barium Sulfate radiopacifying agentincorporated into the polymer matrix for optimum visualizing duringfluoroscopic maneuvering to a desired location. The catheter 18 can becoated with an anti-microbial agent and an anti-clotting agent ifdesired.

Now referring to FIG. 4, the details of the connector manifold 44 can beseen. As shown, the preferred connector manifold 44 is flat andwedge-shaped, with the distal end 82 of the connector manifold 44 beingnarrower than the proximal end 84. Within the connector manifold 44,plural channels 86 are established. As can be appreciated in referenceto FIG. 4, each channel 86 establishes a respective pathway for fluidcommunication between a respective connector line 20, 24, 32, 38 and arespective lumen 54, 56, 58, 60. Owing to the wedge shape of theconnector manifold 44, the tubes 20, 24, 32, 38 are closely juxtaposedto each other near the distal end 82 of the connector manifold 44.

In making the connector manifold 44, the tubes 20, 24, 32, 38 arepositioned on what will become the interior of the connector manifold,and the catheter body 46 likewise is positioned on the connectormanifold, closely spaced from the distal ends of the tubes. A respectivemandrel is then advanced into each tube and the lumen of the catheterbody 46 that is to communicate with the tube. Next, plastic is directedover and around the tubes, mandrels, and catheter body 46 by insertmolding. The mandrels are removed after the plastic hardens,establishing the channels 86.

As envisioned by the present invention, the structure set forth abovecan be used in many medical applications to cool a patient and/or tomaintain temperature in a normothermic or hypothermic patient, forpurposes of improving the medical outcomes of patients on whom, e.g.,aneurysm surgery is to be performed, preferably while the patient'stemperature is below normal body temperature. The structure can then beused to rewarm the patient in a controlled manner by circulating warmcoolant through the structure, or by otherwise regulating natural bodyrewarming by circulating coolant that is maintained at an appropriatecool (relative to normal body temperature) or warm (relative to normalbody temperature) temperature through the structure.

As another example, head trauma can be treated by and after lowering andmaintaining the patient's temperature below normal body temperature. Or,cardiac arrest can be treated while the patient's temperature is belownormal body temperature. Yet again, minimally invasive heart surgery canbe performed on the patient while the patient's temperature is belownormal body temperature. And, cardiac arrest in the patient can betreated by and while the patient's temperature is below normal bodytemperature. Also, the present invention understands that for certainpatients, e.g., stroke victims, it is important to maintain thetemperature of a patient at or below normal body temperature, when thepatient runs or attempts to run a fever. For severe ischemic strokevictims, the malady can be treated by maintaining the patient's bodytemperature at a hypothermic level.

If desired, a temperature sensor 100 such as a thermistor or othersuitable device can be attached to the catheter 18 as shown. The sensor100 can be mounted on the catheter 18 by solvent bonding at a point thatis proximal to the membranes 66, 68. Or, the sensor 100 can be disposedin a lumen of the catheter 18, or attached to a wire that is disposed ina lumen of the catheter 18, with the sensor hanging outside the catheter18. Alternatively, a separate temperature probe can be used, such as theesophageal probe disclosed in co-pending U.S. patent application Ser.No. 09/282,971, filed Mar. 31, 1999 and incorporated herein byreference. As yet another alternative, a rectal probe or tympanictemperature sensor can be used. In any case, the sensor is electricallyconnected to the coolant source 12 for control of the temperature of thecoolant as described in the above-referenced '897 and '940 applications.While the particular CENTRAL VENOUS CATHETER WITH HEAT EXCHANGE MEMBRANEas herein shown and described in detail is fully capable of attainingthe abovedescribed objects of the invention, it is to be understood thatit is the presently preferred embodiment of the present invention and isthus representative of the subject matter which is broadly contemplatedby the present invention, that the scope of the present invention fullyencompasses other embodiments which may become obvious to those skilledin the art, and that the scope of the present invention is accordinglyto be limited by nothing other than the appended claims, in whichreference to an element in the singular is not intended to mean “one andonly one” unless explicitly so stated, but rather “one or more”. Allstructural and functional equivalents to the elements of theabove-described preferred embodiment that are known or later come to beknown to those of ordinary skill in the art are expressly incorporatedherein by reference and are intended to be encompassed by the presentclaims. Moreover, it is not necessary for a device or method to addresseach and every problem sought to be solved by the present invention, forit to be encompassed by the present claims. Furthermore, no element,component, or method step in the present disclosure is intended to bededicated to the public regardless of whether the element, component, ormethod step is explicitly recited in the claims. No claim element hereinis to be construed under the provisions of 35 U.S.C. 112, sixthparagraph, unless the element is expressly recited using the phrase“means for”.

What is claimed is:
 1. A heat exchange catheter, comprising: a catheterbody defining at least a coolant supply lumen and a coolant returnlumen; at least first and second heat exchange membranes disposed alonga distal portion of the catheter body and communicating with one or moreof the lumens, such that coolant can be supplied to the heat exchangemembranes via the coolant supply lumen and received from the heatexchange membranes via the coolant return lumen to effect a closed loopheat exchanger for cooling and/or warming a patient, wherein thecatheter is made of a urethane, said urethane being an aromaticurethane.